Variable brightness and field of view display

ABSTRACT

A display system varies a size of a field of view area of a display for augmented reality (AR) applications based on at least one of ambient light in the environment and content displayed at the display and varying a brightness level of the field of view area such that the brightness level within the field of view area is inversely proportional to the field of view area. Based on an amount of ambient light detected in the environment of the display system, the display system adjusts the size of the area of the field of view of the display in inverse proportion to the amount of detected ambient light. As the size of the field of view area decreases, the display system increases the brightness level of the display within the field of view such that the brightness level is approximately inversely proportional to the field of view area.

BACKGROUND

Display systems for augmented reality (AR) applications compete withambient light in the environment to maintain a contrast level that issufficient for easy understanding of displayed information by a user.Ambient environment brightness covers a wide range of up to 100,000 luxin bright sunlight, creating challenges for the display systems toprovide a brightness level that supports sufficient contrast for asatisfying user experience. For example, in some cases a brightnesslevel of 5000-8000 nits (candelas per square meter) may be needed for adisplay to provide a contrast ratio of 3:1 to minimize cognitive loadfor perceiving the display. However, maintaining a high brightness levelover a wide field of view display increases power consumption and mayexceed local thermal or power constraints or cause failures or reducelifetime of display system elements in the event of operation beyondtheir rated brightness.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may be better understood, and its numerousfeatures and advantages made apparent to those skilled in the art byreferencing the accompanying drawings. The use of the same referencesymbols in different drawings indicates similar or identical items.

FIG. 1 is a perspective view of a display system with a projector tovary a field of view area of the display in inverse proportion to abrightness level of the display in accordance with some embodiments.

FIG. 2 is a block diagram of portion of the display system for adjustinga field of view area of the display based on detected ambient light andcontent displayed at the display in accordance with some embodiments.

FIG. 3 is an illustration of a variable field of view of a display basedon detected ambient light in accordance with some embodiments.

FIG. 4 is an illustration of a variable field of view of a display basedon detected ambient light in accordance with some embodiments.

FIG. 5 is an illustration of a variable field of view of a display basedon detected ambient light in accordance with some embodiments.

FIG. 6 is an illustration of a movable field of view of a display basedon content displayed at the display in accordance with some embodiments.

FIG. 7 is an illustration of multiple fields of view of a display basedon content displayed at the display in accordance with some embodiments.

FIG. 8 is a flow diagram of a method of adjusting a location and size ofa field of view area and brightness of a display based on ambient lightand content displayed at the display in accordance with someembodiments.

DETAILED DESCRIPTION

Field of view generally refers to the extent that a scene is visible toan observer and is usually characterized by the angle formed at the eyebetween respective light beams originating from two points at oppositeedges of a scene that are both visible from the same eye position. Thehuman eye typically has a field of view of almost 180° across thehorizontal direction and about 135° across the vertical direction. Anear eye display system typically has a field of view that is less thanthe field of view of the eye. In general, a near eye display systemimplementing a larger field of view has overall higher power consumptionbecause, at least in part, of increased light signal generationnecessary to fill the larger field of view.

FIGS. 1-8 illustrate techniques for varying (e.g., controlling) a sizeof a field of view area of a display system for augmented reality (AR)applications based on at least one of ambient light in the environmentand content displayed at the display and for varying (e.g., controlling)a brightness level of the field of view area such that the brightnesslevel within the field of view area is inversely proportional to thefield of view area. In some embodiments, the display system is a neareye display system that includes an ambient light sensor and a display.The ambient light sensor detects an amount of ambient light in theenvironment of the display system. Based on the amount of detectedambient light, the display system varies the size of the area of a fieldof view of the display in inverse proportion to the amount of detectedambient light. For example, if the amount of ambient light is relativelyhigh, the display system reduces the area of the field of view. Byvarying the field of view based on the amount of detected ambient light,the display system increases contrast (i.e., the ratio of displaybrightness to ambient brightness) without increasing power consumption.

As the display system reduces the area of the field of view, the displaysystem also increases the brightness level of the display within thefield of view such that the brightness level is approximately inverselyproportional to the field of view area. The display system uses ascanning projection system in some embodiments, wherein the displaybrightness at a given portion of the display is a function of the amountof time spent at the portion. As the total field of view area swept bythe projector shrinks, the time spent at any given point within thefield of view area increases, thus increasing the apparent displaybrightness. In some embodiments, the time spent at any given pointincreases due to either extended dwell time (i.e., a slower scan), ormore instances within a fixed time (i.e., an increased number of scansacross a specific point or angle).

In some embodiments, the display system varies the location or size ofthe field of view area of the display based on the content beingdisplayed. For example, in some embodiments, the display system displaysa notification of an incoming message at a location on the display thatis likely to capture the user's attention without blocking the user'sview of other visual information that is important for the user'sexperience.

FIG. 1 illustrates a display system 100 with a projector 120 configuredto adjust a scan size and field of view area 130 of a display at one orboth of lens elements 140, 145 in inverse proportion to a brightnesslevel of the display in accordance with some embodiments. In theillustrated example, display system 100 includes a support structure 110that in use is worn on the head of a user and has a general shape andappearance of an eyeglasses (e.g., sunglasses) frame. Support structure110 carries components including the projector 120, a controller 150, aforward-facing camera 155, and an ambient light sensor 160 that detectsa level of ambient light in the environment of the display system 100.In some embodiments, portions of the projector 120 and controller 150are contained within an inner volume of support structure 110; however,FIG. 1 provides a partial-cutaway view in which regions of the supportstructure 110 have been removed in order to render visible portions ofthe projector 120 and controller 150 that would otherwise be concealed.Components of the display system 100 are implemented as hardware,firmware, software, or any combination thereof. In some embodiments, thedisplay system 100 has a different shape and appearance from theeyeglasses frame depicted in FIG. 1 . Further, in some embodiments thedisplay system 100 includes one or more software, hardware, and firmwarecomponents in addition to or different from those shown in FIG. 1 .

The forward-facing camera 155 captures image data of the localenvironment of the display system 100. In some embodiments, the displaysystem 100 includes one or more additional forward-facing cameras (notshown) having fields of view that overlap starting at a specifieddistance from the display system 100, thereby enabling depth sensing ofobjects in the local environment that are positioned in the region ofoverlapping field of view via image analysis.

The display system 100 includes lens elements 140, 145 one or both ofwhich include a material to direct an image or graphic to the user'seye. In addition, each of the lens elements 140, 145 is sufficientlytransparent to allow a user to see through to provide a field of view ofthe user's real-world environment. In some embodiments, the lenselements 140, 145 act as a combiner in a light projection system andinclude a coating that reflects the light projected onto them from theprojector 120. In embodiments in which the projector 120 is a scanninglaser projector, a reflective coating may not be used.

In some embodiments, the lens elements 140, 145 include a transparent orsemi-transparent matrix display, such as an electroluminescent displayor a liquid crystal display, one or more waveguides for delivering animage to the user's eyes, or other optical elements capable ofdelivering an in focus near-to-eye image to the user. A correspondingdisplay driver (not shown) is disposed within the support structures110, 115 for driving such a matrix display. The lens element 140 providean augmented reality display in which a virtual representation can besuperimposed over or provided in conjunction with a real-world view asperceived by the user through the lens element 140. In the depictedembodiment, the visual representation is a projected image projected bythe projector 120 onto an inside surface of the lens element 140. Insome embodiments, a second projector (not shown) is contained within aninner volume of the support structure 115 and projects light onto aninside surface of the other lens element 145.

In some embodiments, the projector 120 is a digital lightprocessing-based projector, a scanning laser projector, or anycombination of a modulative light source such as a laser or one or moreLEDs and a dynamic reflector mechanism such as one or more dynamicscanners or digital light processors. In some embodiments, the projector120 includes multiple laser diodes (e.g., a red laser diode, a greenlaser diode, and/or a blue laser diode) and at least one scan mirror(e.g., a single two-dimensional scan mirror or two one-dimensional scanmirrors, which may be, e.g., micro-electromechanical system (MEMS)-basedor piezo-based). The projector 120 is communicatively coupled to (andsupport structures 110, 115 may further carry) the controller 150 and anon-transitory processor-readable storage medium or memory storingprocessor-executable data and/or instructions that, when executed by thecontroller 150, cause the controller 150 to control the operation of theprojector 120.

The controller 150 controls a scan area size and scan area location forthe projector 120 and is communicatively coupled to the ambient lightsensor 160 and to a processor (not shown) that generates content to bedisplayed at the display system 100. The projector 120 projects lightover a variable area called the field of view of the display system 100.The scan area size corresponds to the size of the field of view area andthe scan area location corresponds to the region of the lens element140, 145 at which the field of view area is visible to the user.

The ambient light sensor 160 detects an amount of ambient light in theenvironment of the display system 100. In some embodiments, the ambientlight sensor 160 compares the detected amount of ambient light to one ormore thresholds (not shown) and communicates information regarding theamount of detected ambient light or whether the amount of detectedambient light exceeds or is less than the one or more thresholds to thecontroller 150. In some embodiments, the ambient light sensor 160 takesmeasurements of ambient light at a different frequency than theforward-facing camera captures images of the environment. For example,an ambient light reading may be taken only once for every N image framecaptures from the forward-facing camera 155, where N may be an integerlarger than one.

In operation, the ambient light sensor 160 communicates informationregarding the amount of ambient light detected in the environment to thecontroller 150. The controller 150 determines a size of one or morefield of view areas and location(s) of the one or more field of viewareas on the lens elements 140, 145 based on the amount of ambient lightdetected in the environment and/or content being displayed at thedisplay system 100. The controller 150 controls the projector 120 toscan only within a scan area that produces the field of view area andlocation selected by the controller 150 based on the amount of detectedambient light and/or the content displayed at the display system 100.For example, in some embodiments the controller 150 adjusts an angle ofthe MEMS-based scan mirror to control the scan area and location. Insome embodiments, the controller 150 selects a field of view area sizein inverse linear proportion to the amount of ambient light detected bythe ambient light sensor 160 to maintain a comfortable contrast ratiowith the ambient environment.

For example, if the ambient light sensor 160 detects a large amount ofambient light, such as in bright sunlight, the controller 150 reducesthe field of view area, whereas if the ambient light sensor 160 detectsa small amount of ambient light, such as in a dimly lit room, thecontroller 150 increases the field of view area. As the field of viewarea contracts, the amount of time the projector 120 spends projectinglight at any given point in the scan area increases, thus increasing thebrightness level perceived by the user within the scan area. By varyingthe field of view area and brightness level based on the detectedambient light level, the controller 150 supports daytime visibility ofthe display system 100 without exceeding local thermal or powerconstraints. For example, in a dimly lit environment, the controller 150sets a field of view area (e.g., measured in mm²) to 16×12 at 3000 nits.As the display system 100 moves to a more brightly lit environment, thecontroller 150 reduces the field of view to 8×12 and increases thebrightness within the field of view to 6000 nits, or splits the field ofview into two separate 6×6 fields of view, each having a brightness of8000 nits.

In a dimly lit environment, the controller reduces the brightness levelby expanding the field of view area. However, at some field of view areasize, the projector 120 exceeds the field of view capability of theoptics between the projector 120 and the user's eye (referred to asopening the MEMS angle beyond the relay optics field of view). In someembodiments, the controller 150 dynamically tunes the angle of theMEMS-based scan mirror to overdrive a fast MEMS for a semi-continuousline, thus dimming the displayed content. By overdriving the MEMS for asemi-continuous line, the controller 150 provides enhanced dynamic rangein low brightness scenarios.

In some embodiments, the controller 150 varies the field of view areasize, brightness level, and/or location based on content displayed atthe display system 100. To illustrate, if the content includes an urgentmessage or visual interface for a user experience, the controller 150controls the projector 120 to scan an area having a size and/or locationat the lens elements 140, 145 adapted to enhance the user experience.Thus, for example, if the image data of the local environment capturedby the forward-facing camera 155 indicates the presence of obstacles orother hazards in the local environment, the controller 150 places thefield of view area in a location on the lens elements 140, 145 that doesnot obscure the obstacles or other hazards while still capturing auser's attention.

FIG. 2 is a block diagram of a portion 200 of the display system 100 ofFIG. 1 for adjusting a field of view area of the display based ondetected ambient light and content displayed at the display inaccordance with some embodiments. The controller 150 includes a field ofview (FOV) size selector 230, a FOV location selector 240, and abrightness controller 250. The FOV size selector 230, the FOV locationselector 240, and the brightness controller 250 are each implemented ashardware, firmware, software, or any combination thereof.

The controller 150 receives inputs from the ambient light sensor 160, aprocessor 220, and the forward-facing camera 155. The ambient lightsensor 160 provides ambient light data 225 indicating an amount ofambient light detected in the environment of the display system 100 tothe controller 150. The processor 220 provides content 235 for displayat the display system 100 to the controller 150. The content 235includes images for display at the display system 100. Theforward-facing camera 155 provides image data 210 representing theenvironment of the display system 100 to the controller 150.

Based on one or more of the ambient light data 225, the content 235, andthe image data 210, the FOV size selector 230 determines a size of thefield of view area in which images are displayed at the lens elements140, 145 and the brightness controller 250 determines the brightness ofthe displayed content within the field of view area. In someembodiments, the FOV size selector 230 selects a smaller field of viewarea in response to the ambient light data 225 indicating a highbrightness level in the environment of the display system 100 andselects a larger field of view area in response to the ambient lightdata 225 indicating a low brightness level in the environment such thatthe size of the field of view area is inversely proportional to thelevel of ambient light in the environment. The brightness controller 250varies the brightness of the displayed content in inverse proportion tothe size of the field of view area such that the brightness of thecontent displayed at the display system 100 increases as the size of thefield of view area decreases, and the brightness of the contentdisplayed at the display system 100 decreases as the size of the fieldof view area increases.

The FOV size selector 230 additionally bases the determination of thesize of the field of view area on the content 235. For example, if thecontent 235 includes an urgent notification, the FOV size selector 230either increases the size of the field of view area so that the content235 appears across a larger portion of the lens elements 140, 145, ordecreases the size of the field of view area while the brightnesscontroller 250 increases the brightness of the displayed content 235 sothat the displayed content 235 is more likely to capture the user'sattention.

The FOV location selector 240 determines one or more locations of thefield of view area(s) within the user's field of view based on at leastone of the content 235 and the image data 210. The FOV location selector240 selects a location of the field of view area to allow the visualinterface for an experience to be placed in a location within the user'sfield of view that enhances the experience. For example, in someembodiments, the FOV location selector 240 selects a location of thefield of view area based at least in part on the image data 210 suchthat the field of view area does not obstruct the user's view of anyobstacles or hazards in the user's environment.

The controller 150 controls the size, brightness, and location of thescan area of the projector 120 by providing field of view size,location, and brightness information 260 to the projector 120. Based onthe information 260, the projector 120 adjusts the scan angle andduration at each point of the scanned area to project an image of thecontent 235 having a field of view area at a location and having a sizeand brightness based on the ambient light data 225, the content 235, andthe image data 210.

FIG. 3 is an illustration 300 of a variable field of view 315 of adisplay 310 based on detected ambient light in an environment 305 of thedisplay system 100 in accordance with some embodiments. In the depictedexample, the amount of ambient light in the environment 305 is low. Theambient light sensor 160 detects the low level of ambient light andprovides the ambient light data 225 to the controller 150. The FOV sizeselector 230 and the brightness controller 250 determine the size andbrightness of the field of view area 315 based on the ambient light data225. Because the ambient light data 225 indicates a low level of ambientlight, the controller 250 provides field of view size and brightnessinformation 260 to the projector 120 indicating that the size of thefield of view area 315 is large and the brightness of the projectedcontent 235 is low. The projector 120 adjusts the scan angle andduration at each point of the scanned area to project an image of theprojected content 320 having the field of view area 315 and a relativelylow brightness.

FIG. 4 is an illustration 400 of a variable field of view 415 of adisplay 410 based on detected ambient light in an environment 405 of thedisplay system 100 in accordance with some embodiments. In the depictedexample, the amount of ambient light in the environment 405 is higherthan the amount of ambient light in the environment 305 of FIG. 3 . Theambient light sensor 160 detects the relatively higher level of ambientlight and provides the ambient light data 225 to the controller 150. TheFOV size selector 230 and the brightness controller 250 determine thesize and brightness of the field of view area 415 based on the ambientlight data 225. Because the ambient light data 225 indicates arelatively higher level of ambient light, the controller 250 providesfield of view size and brightness information 260 to the projector 120indicating that the size of the field of view area 415 is relativelysmaller than the size of the field of view area 315 of FIG. 3 and thebrightness of the projected content 235 is relatively higher than thebrightness of the projected content 235 of FIG. 3 . The projector 120adjusts the scan angle and duration at each point of the scanned area toproject an image of the projected content 420 having the field of viewarea 415 and a relatively higher brightness.

FIG. 5 is an illustration 500 of a variable field of view 515 of adisplay 510 based on detected ambient light in an environment 505 of thedisplay system 100 in accordance with some embodiments. In the depictedexample, the amount of ambient light in the environment 505 isrelatively high. The ambient light sensor 160 detects the high level ofambient light and provides the ambient light data 225 to the controller150. The FOV size selector 230 and the brightness controller 250determine the size and brightness of the field of view area 515 based onthe ambient light data 225. Because the ambient light data 225 indicatesa high level of ambient light, the controller 250 provides field of viewsize and brightness information 260 to the projector 120 indicating thatthe size of the field of view area 515 is small and the brightness ofthe projected content 235 is high. The projector 120 adjusts the scanangle and duration at each point of the scanned area to project an imageof the projected content 520 having the field of view area 515 and arelatively high brightness.

FIG. 6 is an illustration 600 of a movable field of view 615 of adisplay 610 based on content 620 displayed at the display in accordancewith some embodiments. In the depicted example, the environment 605 ofthe display device 100 includes a walkway with walls on either side thatintersects with another walkway. The forward-facing camera 155 capturesimage data 210 of the environment 605 and provides the image data 210 tothe controller 150. The FOV size selector 230 determines a size of thefield of view area 615 and the FOV location selector 240 determines alocation of the field of view area 615 to display projected content 620based on the content 620 and the image data 210. The brightnesscontroller 250 determines a brightness level of the field of view area615 and the projected content 620 based on the size of the field of viewarea 615 and the content 620. In the illustrated example, the controller150 selects a location and size of the field of view area 615 that doesnot obstruct the user's view of the intersection of the two walkways.The projector 120 adjusts the scan angle and duration at each point ofthe scanned area to project an image of the projected content 620 havinga field of view area 615 that is sized and located within the display610 to enhance the user's experience.

FIG. 7 is an illustration 700 of multiple fields of view 715 of adisplay 710 based on content 720 displayed at the display in accordancewith some embodiments. In the depicted example, the environment 705 ofthe display device 100 includes a walkway with walls on either side thatintersects with another walkway. The forward-facing camera 155 capturesimage data 210 of the environment 705 and provides the image data 210 tothe controller 150. The FOV size selector 230 determines a number andsize of the field of view areas 715 and the FOV location selector 240determines locations of the field of view areas 715 to display projectedcontent 720 based on the content 720 and the image data 210. Thebrightness controller 250 determines a brightness level of the field ofview areas 715 and the projected content 720 based on the sizes of thefield of view areas 715 and the content 720. In the illustrated example,the controller 150 selects locations and sizes of the field of viewareas 715 that do not obstruct the user's view of the intersection ofthe two walkways. The projector 120 adjusts the scan angle and durationat each point of the scanned areas to project images of the projectedcontent 720 having field of view areas 715 that are sized and locatedwithin the display 610 to enhance the user's experience.

FIG. 8 is a flow diagram of a method 800 of adjusting a location andsize of a field of view area and brightness of a display based onambient light detected in the environment, image data, and contentdisplayed at the display in accordance with some embodiments. The method800 is described with respect to an example implementation at thedisplay system 100 of FIGS. 1 and 2 . At block 802, the controller 150receives ambient light data 225 from the ambient light sensor 160. Atblock 804, the controller 150 receives image data 210 from theforward-facing camera 155. At block 806, the controller 150 receives andanalyzes content 235 for display at the display device 100.

At block 808, the FOV size selector 230 determines dimensions of thefield of view area(s) based on the ambient light data 225, the content235, and the image data 210. The FOV location selector 240 determinesone or more locations to place the field of view area(s) at the displaybased on the image data 210 and content 235. The brightness controller250 determines a brightness level for the projected content based on thefield of view size.

At block 810, the controller 150 controls the size, brightness, andlocation of the scan area of the projector 120 by providing field ofview size, location, and brightness information 260 to the projector120. Based on the information 260, the projector 120 adjusts the scanangle and duration at each point of the scanned area to project an imageof the content 235 having a field of view area at a location and havinga size and brightness based on the ambient light data 225, the content235, and the image data 210. The controller 150 controls the projector120 to scan an area to project one or more field of view areas, eachhaving a size that is inversely proportional to the amount of ambientlight detected in the environment of the display system 100 and toproject the content 235 with a brightness that is inversely proportionalto the size of the field of view area. In some embodiments, thecontroller 150 controls the projector 120 to scan in an area thatproduces a field of view area that is located at the lens elements 140,145 (or other display screen) in a location that enhances the user'sexperience based on the content 235 being displayed.

In some embodiments, certain aspects of the techniques described abovemay be implemented by one or more processors of a processing systemexecuting software. The software comprises one or more sets ofexecutable instructions stored or otherwise tangibly embodied on anon-transitory computer readable storage medium. The software caninclude the instructions and certain data that, when executed by the oneor more processors, manipulate the one or more processors to perform oneor more aspects of the techniques described above. The non-transitorycomputer readable storage medium can include, for example, a magnetic oroptical disk storage device, solid state storage devices such as Flashmemory, a cache, random access memory (RAM) or other non-volatile memorydevice or devices, and the like. The executable instructions stored onthe non-transitory computer readable storage medium may be in sourcecode, assembly language code, object code, or other instruction formatthat is interpreted or otherwise executable by one or more processors.

Note that not all of the activities or elements described above in thegeneral description are required, that a portion of a specific activityor device may not be required, and that one or more further activitiesmay be performed, or elements included, in addition to those described.Still further, the order in which activities are listed are notnecessarily the order in which they are performed. Also, the conceptshave been described with reference to specific embodiments. However, oneof ordinary skill in the art appreciates that various modifications andchanges can be made without departing from the scope of the presentdisclosure as set forth in the claims below. Accordingly, thespecification and figures are to be regarded in an illustrative ratherthan a restrictive sense, and all such modifications are intended to beincluded within the scope of the present disclosure.

Benefits, other advantages, and solutions to problems have beendescribed above with regard to specific embodiments. However, thebenefits, advantages, solutions to problems, and any feature(s) that maycause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeature of any or all the claims. Moreover, the particular embodimentsdisclosed above are illustrative only, as the disclosed subject mattermay be modified and practiced in different but equivalent mannersapparent to those skilled in the art having the benefit of the teachingsherein. No limitations are intended to the details of construction ordesign herein shown, other than as described in the claims below. It istherefore evident that the particular embodiments disclosed above may bealtered or modified and all such variations are considered within thescope of the disclosed subject matter. Accordingly, the protectionsought herein is as set forth in the claims below.

1. A method comprising: varying a field of view area of a display based on an amount of ambient light in an environment of the display; and varying a brightness level of the display based on the field of view area.
 2. The method of claim 1, wherein varying the brightness level is further based on content displayed at the display.
 3. The method of claim 1, further comprising: detecting the amount of ambient light in the environment of the display.
 4. The method of claim 3, further comprising: reducing the field of view area of the display in response to detecting an increase in the amount of ambient light in the environment of the display.
 5. The method of claim 4, further comprising: moving a region of the display having a reduced field of view from a first location of the display to a second location of the display based on content displayed at the display.
 6. The method of claim 4, further comprising: splitting the reduced field of view area of the display into two or more reduced field of view areas; and placing the two or more reduced field of view areas at two or more locations of the display based on content displayed at the display.
 7. The method of claim 3, further comprising: increasing the field of view area of the display in response to detecting a decrease in the amount of ambient light in the environment of the display.
 8. The method of claim 1, wherein varying the brightness level comprises varying the brightness level in inverse proportion to the field of view area.
 9. A method, comprising: varying a brightness level of a field of view area of a display in inverse proportion to a size of the field of view area of the display.
 10. The method of claim 9, further comprising: detecting an amount of ambient light in an environment of the display; and varying the field of view area of the display based on the amount of ambient light in the environment.
 11. The method of claim 10, further comprising: reducing the field of view area of the display in response to detecting an increase in the amount of ambient light in the environment of the display.
 12. The method of claim 11, further comprising: moving a region of the display having a reduced field of view from a first location of the display to a second location of the display based on content displayed at the display.
 13. The method of claim 11, further comprising: splitting the reduced field of view area of the display into two or more reduced field of view areas; and placing the two or more reduced field of view areas at two or more locations of the display based on content displayed at the display.
 14. The method of claim 10, further comprising: increasing the field of view area of the display in response to sensing a decrease in the amount of ambient light in the environment of the display.
 15. The method of claim 9, wherein varying the brightness level is further based on content displayed at the display.
 16. A display system, comprising: a display; a projector having a variable scan size to vary an area of a field of view of the display; and a controller to vary a brightness level of the field of view of the display in inverse proportion to the scan size.
 17. The display system of claim 16, further comprising: a sensor to detect an amount of ambient light in an environment of the display system, wherein the projector is adapted to reduce the area of the field of view of the display and the controller is adapted to increase the brightness level of the field of view of the display in response to the sensor detecting an increase in the amount of ambient light in the environment of the display system.
 18. The display system of claim 16, wherein the projector is further adapted to move a region of the display having a reduced field of view from a first location of the display to a second location of the display based on content displayed at the display.
 19. The display system of claim 16, wherein the projector is further adapted to: split the region of the display having a reduced field of view into two or more reduced field of view areas; and place the two or more reduced field of view areas at two or more locations of the display based on content displayed at the display.
 20. The display system of claim 16, wherein the controller is adapted to vary the brightness level based on content displayed at the display. 